Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 169

Temperature # b (or the base temperature) is determined from relation:

Q losses ¼

Þ ¼Q gain

UA ref # i # b ð ð 13 Þ

where

UA ref is the overall heat transfer coef cient of the building in W/ ° C;

￿

20 C; Standard value # i ¼

￿

Q losses is the heat loss of building and is given by the equation:

￿

Q losses ¼ Q envelope þ Q airchanges þ Q perimeter

ð 14 Þ

The terms of equation are:

Q envelope ¼ UA envelope # i # e

ð Þ Envelope loss ''skin'' ð Þ ð 15 Þ

Q Air Changes ¼

UA Air Changes # i # e ð Þ Infiltration loss ''lungs'' ð Þ ð 16 Þ

Q perimeter ¼

UA perimeter # i # e ð Þ Perimeter loss ''feet'' ð Þ ð 17 Þ

Q gain is the heat generated in the building and is given by the equation:

￿

Q gain ¼ Q people þ Q lights þ Q equipments

ð 18 Þ

This results in balance point temperature:

Q losses
UA ref

# b ¼ # i ð 19 Þ

There is considerable uncertainty associated with the determination of the bal-
ance point temperature, but based on the observations of typical buildings, it is
usually taken to be 19

C in Europe.
The rate of energy consumption of the heating system is

- 21 °

UA ref
g h

Q h ¼

ð# b # i Þ ð 20 Þ